Polybacterial Iliopsoas Muscle Abscess as an Indication for Early Diagnosis of Crohn's Disease.

BACKGROUND Crohn disease (CD) is a chronic, relapsing inflammatory bowel disease characterized by penetrations or fistulae in the gastrointestinal tract and abscesses in the surrounding tissues. Diagnosis of CD is difficult with an iliopsoas muscle abscess (IMA) as an initial presentation. CASE REPORT A 22-year-old Japanese man had right hip pain 17 days prior to admission. Because of worsening pain, he was admitted to our hospital. Physical examination revealed limitation of his right hip motion and a positive right psoas sign. Abdominal contrast-enhanced computed tomography (CT) revealed a large right IMA. Continuous drainage, which revealed polymicrobial pus, with intravenous administration of antibiotics dramatically decreased the size of the IMA. The drainage tube was removed on hospitalization day 9 because barium enema and contrast radiography of the abscess through the drainage tube showed no fistula. However, on day 19 of hospitalization, the IMA was redetected by abdominal CT. Continuous abscess drainage was resumed, and the third contrast radiograph of the abscess revealed contrast medium flow into the small intestine. Colonoscopy detected stenoses and circumferential ulceration of the terminal ileum. Histopathological examination of the ileum biopsy showed histocyte aggregation with lymphocyte or plasmacyte infiltration of the lamina propria, compatible with a CD diagnosis. Laparoscopic ileocecal resection was performed on day 64 of hospitalization. CONCLUSIONS Penetration of the intestinal tract caused by CD should be suspected in a patient with a polymicrobial IMA. It is essential to identify the fistula and subsequently perform surgical resection of the affected intestinal area.